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Anatomy & Physiology: Cell Membrane Structure and Transport

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이 집합의 용어 (21)

  • What are the three basic parts of a human cell?
    Plasma membrane (flexible outer boundary), cytoplasm (intracellular fluid with organelles), and nucleus (DNA-containing control center).
  • Describe the structure of the plasma membrane.
    A fluid mosaic model with a bilayer of phospholipids, embedded proteins, and cholesterol that controls what enters and leaves the cell.
  • What are the characteristics of phospholipids in the membrane?
    Phosphate heads are polar and hydrophilic, fatty acid tails are nonpolar and hydrophobic, forming a bilayer.
  • What role does cholesterol play in the plasma membrane?
    Cholesterol is located between phospholipid tails and increases membrane stiffness.
  • Differentiate between integral and peripheral membrane proteins.
    Integral proteins span the membrane and function as transporters, enzymes, or receptors. Peripheral proteins are loosely attached and assist in enzymes, motor functions, and cell connections.
  • What are the two main types of membrane transport?
    Passive transport (no energy required) and active transport (requires ATP).
  • Define simple diffusion.
    Movement of nonpolar, lipid-soluble molecules directly through the phospholipid bilayer down their concentration gradient.
  • What is facilitated diffusion?
    Passive transport of hydrophobic molecules with the help of carrier or channel proteins down their concentration gradient.
  • How do carrier proteins assist in facilitated diffusion?
    They bind specific large polar molecules, change shape, and transport them across the membrane.
  • What are channel proteins and their types?
    Transmembrane proteins with aqueous cores that transport ions; types include leakage channels (always open) and gated channels (open/close by signals).
  • Explain osmosis in terms of membrane transport.
    Movement of water through a selectively permeable membrane via aquaporins, from low to high solute concentration.
  • What is tonicity and its effects on red blood cells?
    Tonicity is a solution's ability to change cell shape by altering water volume: isotonic (normal), hypertonic (cell shrinks), hypotonic (cell swells/lyses).
  • What distinguishes active transport from passive transport?
    Active transport moves solutes against their concentration gradient using ATP energy.
  • Describe the sodium-potassium pump function.
    Pumps 3 Na+ out and 2 K+ in using ATP, maintaining electrochemical gradients essential for excitable cells.
  • What is secondary active transport?
    Uses energy stored in ion gradients created by primary active transport to move other solutes indirectly.
  • What is vesicular transport and its types?
    Movement of large substances via vesicles; includes transcytosis, vesicular trafficking, endocytosis, and exocytosis.
  • Explain endocytosis and its selectivity.
    Process of engulfing substances into vesicles; can be selective via receptor binding or nonspecific.
  • What is phagocytosis?
    Endocytosis 'cell eating' where pseudopods engulf solid particles forming phagosomes, used by macrophages.
  • Describe pinocytosis.
    'Cell drinking' endocytosis where plasma membrane infolds to bring in extracellular fluid and solutes nonspecifically.
  • What is receptor-mediated endocytosis?
    Selective uptake of molecules via plasma membrane receptors binding specific substances like hormones or LDL.
  • How does exocytosis work?
    Vesicles fuse with plasma membrane to eject substances like hormones or wastes, triggered by signals or voltage changes.